DX improvements for :GitFiles

- [x] I have fzf 0.30.0 or above
- [x] I have read through https://github.com/junegunn/fzf.vim/blob/master/README.md
- [x] I have read through https://github.com/junegunn/fzf/blob/master/README-VIM.md
- [x] I have read through the manual page of fzf (`man fzf`)
- [x] I have searched through the existing issues

Hello,

I'd like to ask if you would consider showing the git status of each file when using :GitFiles.

I know that you have already :GitFiles? to show only changed files.

Sometimes, I open :GitFiles (or :Files) and it would be interesting for me to know which files are currently unstaged because it is usually likely that I want to reopen them for more modifications.

Making them a different color, or using a prefix would be cool.

Also, maybe putting the unstaged / modified files, first on the list would be interesting as well.